Electrical furnace.



w. H. HAMPTON. ELECTRICAL FURNACE. APPLICATION FILED FEB. 28, l9l3- Patented Sept. 7, 1915.

2 SHEETSS HEET I.

W. H. HAMPTON; ELECTRICAL FURNACE.

APPLICATION FILED FEB. 28. 1913.

Patentedfiept. 7

1915. 2 SHEETSSHEET 2.

5] m 2 mtoz UNITED STATES PATENT OFFICE.

VILLIAM 'H. HAMPTON, OF NEW YORK, N. Y., .ASSIGNOR TO THE'CONLEY ELECTRIC FURNACE COMPANY, INCORPORATED, 0F WILMINGTON, DELAWARE, A CORPORA- TION OF DELAWARE.

ELECTRICAL FURNACE.

Patented Sept. "7, 1915.

Application filed February 28, 1913. Serial No. 751.258.

To all whom it may concern Be it known that I, W .LLIAM H. HAMP- TON, a citizen of the United States, residing at New York, in the county and State of New York, have invented Improvements in Electrical Furnaces, of which the following is a specification.

This invention relates to electrical furnaces, more especially for metallurgical purposes, though similar" or somewhat modified constructions may be. used for heating mate-- rials of various kinds for different purposes.

In the metallurgical field, the furnace illustrated'herewith is suited more especially for reducing, sublimating, .or distilling and condensing, and may be used, for example,

- ofa composition of low conductivity; and

- the object of the invention is, in general, to secure effective heating bysuch means, to

avoid clogging, and to provide advantageous means for the collection and escape of gases and vapors The-furnace is an uprlght structure, the

material being fed in at the top and descending in a stream through the interior, Where it is heated as it flows, and-the molten material beingcollectedat the bottom where it may be drawn ofi continuously or intermittently, as desired. The interior of the furnace above the hearth, that is to say the portion which may be termed the shaft of the furnace, is provided with guide members, in-

ternally heated-to a predetermined degree, which. are in staggered relation to each other and provided with reversely-sloping surfaces which guide the material back and forth from side to side and downwardly. Between the guide membersare cavities, which guard against choking and serve to collect gases and vapors, which are allowed to escape through suitable ducts leading from the cavities. Part or all of the sloping surfaces of the .guide members are heated by resistance 'elements, and the heating of the material is; effected as it flows over them.

The heating is especially effective because it takes place While the material is flowing comparatively slowly over the-sloping surgered positions in its interior.

faces and by reason of the fact. that the material in passing from one surface to another, and thus changing its direction of flow, is turned over and over, so that all particles are subjected to the heat. This action also thoroughly mixes the material. The

' resistance elements are protected from contact with the charge or with gases formed in or admitted to the shaft, by being embedded or inclosed in the guide member.

In the-accompanying drawings illustratmg the invention: Figure l is a vertical section through the furnace; Fig. 2 is a section on the line 6-1). of Fig. 1 Fig. 3 is a h rizont'al section on the line aa of Fig. 1; Fig. 4 is a side elevationof the furnace on a reduced scale showing the electrical connections.

The furnace has a hopper 10 at the top, i

into which the material is fed and from which it is delivered by a spiral conveyer 11, or other suitable means, to an opening 12 which admits to the interior of the furnace.

It will be understood that when the invention is used for the reduction of zinc or the like the'feed mechanism does not admit air, which is excluded from the interior of the furnace. The interior of the furnace is constructed like a shaft, with a plurality of guide membersarranged to cause the material to fiow back and forth while gradually descending in the shaft. At the bottom of the furnace is provided a hearth 13, or other suitable means, for receiving the material that finally drops from the lowermost guide members.

The guide members are preferably in the nature of-blocks set into the side walls of the shaft and occupying relatively stag- As shown, they comprise blocks 14, projecting inward from two opposite sides of the shaft or well, and intermediate blocks 15, 16. The blocks are of generally triangular shape, so as to present reversely-sloping surfaces for guiding the material, and to partially inclose cavities 17, 18, which connect with each other by the relatively narrow gaps 19, 20, left between the lower edges of the several blocks and the sloping surfaces of the respective blocks next beneath. These cavities prevent clogging and afford pockets for the collection of gases or vapors, which are permitted to escape through ports 21 to inclined passages 22, I leading diagonally downward through one of the walls of the furnace to a space or condenser 23 at one side. The condenser may be built into one of the walls of the furnace, as shown, and part or all of the passages-22 areextending to the opposite side of the furnace,- where they are closed by plugs 24, by virtue of which the passages can readily be cleaned.

The bottoms of the triangular blocks 14, 15, 16 are preferably approximately horizontal, that is to say, they do not incline upward to the gaps 20 so as to tend todirect the gases to these points, and in addition they are preferably recessed at their underside, for example, in the manner shown, so as to contribute to the pocketing of the gases and vapors, and it is from these recesses,.1mmediately beneath the blocks, that the ports 21 lead.

The sloping surfaces of the guide members are heated by non-metallic resistance bars or plates 25, made, for example, of a composition of clay and graphite in such proportions as to be of low conductivity, preferably about sixty per cent. (60%) of clay to forty per cent. (40%) ,of carbon. These heating elements in the best embodiment of the invention are located inside the guide members, 'so as to be out of contact with the material or gases. The resistance elements may be'formed or inserted in the guide blocks in different manners. For example, the blocks may be sectional, as shown, with a recess formed in one or both sections and occupied by the heater. In the particular construction shown, the blockscomprise surface'portions 26 and body portions 27, which fit into the surface portions and are provided with the cavities in which the resistance conductors are seated. The blocks, composed, may be molded tiles, and the surface sections 26 are preferably of such character, for example carborundum tile, as to withstand the action of the material passing over them, thus constituting highly protective facings covering the heating elements. The walls of the furnace and the blocks are of non-conducting material, so that the current cannot pass through the charge. The sides-of the furnace are also provided with a suitable lining, indicated at 28,- and the blocks may be set at their ends into this lining. The blocks with the resistance elements are accordingly easily removable and reparable, and part or all of these members arepreferably. made of the same sizes, so as to be interchangeable.

The top central block 15 is located with its 'dge directly below the feed orifice 12, so

- t at the material is divided into two por tions which pass down the opposite sloping sides of the block. These sloping surfaces approach the sloping surfaces of the side blocks 14, immediately'below leaving com" I or the sections of which they are pass from highly heated as it passes over the different sloping surfaces. Much the greater portion of this travel is over these heated surfaces, the gaps 20 being comparatively narrow; yet the construction is such that narrow passages of any length are avoided and ample cavities 17, 18 are afforded, so that choking is prevented.

In the case of zinc, for example, the usual charge of a mixture of zinc ore and carbonaceous material, such as ordinarily used in retort furnaces and which has been pre viously roasted, is fed into the upper end of the furnace and the zinc is reduced and distilled during the zigzag descent of the material by gravity. During the passage through the furnace the material remains substantially unfused until it reaches the hearth of the furnace and shrinks in volume because of the combustion of the carbon by means of the oxygehfof the zinc oxid and because of the vaporization of the reduced zinc. The vapors and gases pass out through the ports 21 to the condenser 23, where the zinc vapors condense from which the liquid zinc may be drawn off from time to time or, continuously if desired. The heat for introducing and maintaining the reactions is supplied by the;electric'heaters,

which become incandescent on passage of the current and are ,capable of yielding a high degree of heat. The upper end of the condenser" communicates with a secondary condenser 30 where any vapor of metal or mechanically carried material that may have been carried along 1s condensed, settled and collected. 'The' gases thence pass on through the conduit 31 to any point, where they may be discharged or utilized. Since all of the carbon monoxid generated passes outithrough the delivery end, the gas may be reburned or used.

The furnace may be provided at the bottom with means for the production of'ferro silicon from the zinc residues which finally the lowest guide members and which usually contain iron and silica. This is accomplished by providing one or more resistance heating elements 32 at the sides of or about the hearth 13, this heaterbeing adapted to produce a higher degree of heat than those above, so as to produce the neces sary reactions and render the residues molten. When the furnace is operated with this end in view, a sufficiency of iron in the form of oxid, together with additional carbon are added to the charge so that the iron is reduced and combines with the silica, which is the main constituent of the residues to form a ferro silicon of any desired proportions. I

The connections of the resistance heaters are shown more particularly in Figs. 3' and 4. The opposite ends of the elements 25 project beyond the blocks or tiles in which they are embedded and are cemented or otherwise suitably united to intermediate socket members 33 of a higher degree of conductivity, such, for example, as would be secured by maldng these members of the same composition as the heating elements, but in the proportions of about forty per cent. (40%) of clay to sixty per cent. (60%) of carbon, and these members are 1n turn connected to pure carbon terminals 34. The intermediate members 33 are embedded in the furnace walls and the terminals 34 project outside, being bolted or otherwise secured to branches 35, 36 of vertical bus-bars 37. The resistance conductors 32 are connected in a similar manner to the bus-bars 37 and are adapted to produce a higher temperature at the hearth than in the shaft above. To this end they are of adequate size and are supplied with a suitable amount of current.

Figs. 4: and 5 indicate diagrammatically an arrangement for independently and relatively controlling the heat of the elements 25 and 32. t

, 50 represents a transformer, the secondary of which is connected by parallel circuits 51, 52 with the bus-bars 37 and 37 Rheostats .53, 5l enable the'cu'rrent supplied to the two sets of resistance conductors to be varied.

Means are provided for controlling the flow of the material over the sloping surfaces and through the shaft, so as to regulate the'volumeor depth of the streams or sheets and the velocity of flow. To this end gates ,or valves, such as are herein schematically illustrated at, 55, 56, are provided to regulate the opening at the top gaps 19 and consequently the amount of material flowing therethrough; and in like manner a gate 57 controls the outflow at the bottom of the shaft. By moving the valves in or out the extent of opening at the entrance'and discharge ends of the shaft can be decreased or increased. It maynot be necessary in all instances to provide or utilize gates at both ends of the shaft. Different modes of operating the gates are indicated. Thus the gate 55 occupies an opening in the side wall of the furnace, in which it may be moved in and out horizontally. The member 56 has a rod and handle 58 passing through the top of the furnace, by which it may be moved up and down, the valve being held at may be employed.

What I claim as new is: 1. An electrical furnace for the reduction of zinc or the like provided interiorly with a a staggered arrangement of guide members extending in proximity to each other and partially-inclosing a plurality of connecting cavities with sloping surfaces over which the material flows from one to another in a zigzag downward course, non-arcing resistance means in the interior of said guide members for internally heating the surfaces thereof so as to heat the material as it flows thereover, and means for leading off at different-levels from said cavities the material vaporized from the charge.

. 2. An electrical zinc-reduction furnace having a shaft from which air is excluded, refractory blocks therein, provided with reversely sloping surfaces to change the direction of the flow of the material, non-arcing carbonaceous resistance conductors located inside part or all of said blocks, and means for conducting off and condensing the zinc vapor. I

3. An electrical zinc-reduction furnace, comprising a shaft from which air is excluded, a staggered collection of guide members comprising central triangular refractory blocks and lateral blocks affording a lurality of zigzag communicating passages iiaving sloping surfaces over which the material travels back and forth downwardly, means for heating the charge as it flows over said surfaces comprising electrical resistance elementscomposed of a mixture of clay and graphite embedded within said blocks, and-means for conducting off the zinc vapor from the shaft.

4. An electrical furnace for the reduction of zinc or the like, comprising a shaft from which air is excluded, a plurality of guide members in staggered relation therein having reversely sloping surfaces over which the material travels by gravity in a succession of. downward slides, non-arcing resistance means located entirely within said members for internally heating said surfaces to a high degree of heat so as to heat the material as it flows thereover, and means for conducting olf the liberatedvapors at different levels from beneath said guide members.

5. An electrical furnace having a shaft and a plurality of triangular guide blocks therein arranged in staggered relation so that the material in descending slides in a zigzag course over their surfaces, said blocks comprising upper and lower sections fitted recesses beneath the guide members.

7. An electric furnace having guidemembers provided with high resistance carbonaceous heaters in the interior of the guide members, said guide members having sloping surfaces arranged in zigzag relation and spaces beneath the guide members, a cc denser, and ducts leading from said spaces to said condenser.

8.'An electric furnace having internal guide members provided with sloping surfaces arranged so as to cause the material to descend in a zigzag manner, spaces between the guide members constituting gas or vapor collecting'cavities, high resistance conductors for heating part or all of the guide members, said resistance conductors being arranged within the guide members, and gas outlets leading from the several cavities and discharging outside the furnace chamber into a conduit.

9. An electric furnace having staggered blocks in its interior provided with nonmetallic resistance heating elements in the interior of said blocks and reversely sloping surfaces extending into proximity with. each other and arranged to divide the material into two or more zigzag streams, and means for according a controllable slot-like aperture or apertures through which the material is supplied to said heated surfaces.

10. An electric furnace having a shaft provided interiorly with a plurality of staggered blocks having sloping surfaces over which the material flows in a zigzag manner, said blocks being arranged to divide the material into two or' more streams and'containing in their interiors non-metallic re-' sistance elements for heating their surfaces, one or more gates for controlling the supply of material to said blocks, and one or more gates for controlling the eXit of the material therefrom.

11. An electric furnace for the reduction of zinc or the like having a shaft from which air is excluded, means for feeding the material into the top thereof, and a staggered collection of refractory guide members therein having sloping surfaces extending into proximity with each other and arranged to divide the material into two or more streams which alternately diverge and converge in their downward flow over said surfaces, electrical non-metallic resistance means located in the interior of .part or all of said guide members, condensing means, and

- ducts leading thereto from different levels.

12. An electrical Zinc reduction furnace having a shaft into which the material is fed at the top, resistance heating elements arranged to heat the material as it descends, a condenser connected with the shaft, a

hearth at the bottom of said shaft, and res sistance heating means at the hearth adapted to produce a more intense heat for the production of ferro silicon.

13. An electrical zinc reduction furnace having a shaft into which material is fed at the top, resistance heating elements arranged at different levels to heat the material as it descends, a condenser connected with the shaft, a hearth forming the lower part of the shaft, and resistance heating means in the walls of the hearth adapted to produce a more intense heat for the production of .ferro silicon.

14:. An electrical zinc reduction furnace having a downward extending opening, means for feeding the material to said opening to descend therein, resistance means for heating the material as it descends, a plurality of gas and vapor ducts leading from said opening, a condenser connected therewith, and common means for collecting and taking off the gases from said plurality of ducts. 15. The method of zinc reduction with production of erro silicon from the residues, conniris causing the material mixed with carbon .101 the reduction of the zinc and an added suliiciency of iron in the form of oxid and carbon for the reduction of the ferro silicon to pass downward through an air excluding space, heating the material as it descends to bring about the reduction of the zinc, and heating the residues at the bottom to a higher temperature to fuse the residues and cause the formation ofi ferro sil con.

16. The method of reducing zinc, which comprises miXing the ore with carbon and iron, heating the mixture so as to distil off the zinc, and subjecting the residue to a higher temperature sufficient to fuse th m and cause the formation of ferro silicon.

17. An electric furnace, comprising a shaft containing a vertical series of guide blocks spaced from each other and each having two sides sloping downward from the top in reverse directions, series of guide blocks at opposite sides of the first-mention'ed series and having guide surfaces sloping toward and into proximity with the sloping sides of the intermediate blocks,

directions,

vcomprising an air-excluding shaft containmg' a vertical series of guide blocks spaced from each other and each having two sides sloping downward from the top in reverse series of guide blocks at opposite sides of the first-mentioned series and having guide surfaces sloping toward and into proximity with the sloping sides of the intermediate "blocks, whereby two or more zigzag communicating passages for the material are afforded, carbonaceous resistance bodies contained inside of and beneath the surface of part or all of said blocks for heatmg said surfaces by the passage of electric current therethrough, and means for conducting 0H and condensing zinc vapor.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing'witnesses. 1

WILLIAM H. HAMPTON.

Witnesses:

FREDERICK KANz, LoRELLA F. LITTLE 

